SpaceXAI: Grok 4.6 vs OpenAI: GPT-5.6 Luna
Side-by-side comparison of specs, pricing, benchmark scores, and task rankings. Updated 2026-11-12.
| SpaceXAI: Grok 4.6 | OpenAI: GPT-5.6 Luna | |
|---|---|---|
| Vendor | x-ai | openai |
| Quality Score | 100 | 100 |
| Input Price | $2.00/M | $0.20/M |
| Output Price | $6.00/M | $1.20/M |
| Context Window | 500,000 | 1,050,000 |
| Max Output | 450,000 | 128,000 |
| Tool Calling | ✓ | ✓ |
| Structured Output | ✓ | ✓ |
| Reasoning Mode | ✓ | ✓ |
| Vision | ✓ | ✓ |
| Audio | - | - |
The verdict
For a sample job of 1 million input tokens and 250,000 output tokens, GPT-5.6 Luna costs $0.50 and Grok 4.6 costs $3.50, so GPT-5.6 Luna is about 7.0 times cheaper for the same work.
GPT-5.6 Luna reads up to 1,050,000 tokens at once, roughly 1,575 pages of text, against about 750 pages for Grok 4.6.
Across the 10 tasks where they differ, GPT-5.6 Luna on 10 (SQL Generation, Code Completion, Code Documentation and others).
Grok 4.6 was released in August 2026 and GPT-5.6 Luna in July 2026.
Pick GPT-5.6 Luna if you need lower cost, long documents or the stronger all-round task scores.
Costs use current list prices per million tokens; page counts assume about 0.75 words per token and 500 words per page.
Who wins by task?
| Task | SpaceXAI: Grok 4.6 | OpenAI: GPT-5.6 Luna |
|---|---|---|
| SQL Generation | 133 | 133 |
| Code Completion | 118 | 131 |
| Code Documentation | 130 | 131 |
| Regex Writing | 118 | 119 |
| CSV / Spreadsheet Cleanup | 133 | 133 |
| JSON Extraction | 122 | 131 |
| Bulk Data Labeling | 119 | 129 |
| Long-Document Summarization | 137 | 137 |
| Short-Form Summarization | 114 | 123 |
| Blog Post Writing | 121 | 121 |
Scores reflect capability match + benchmark data + pricing for each task. Methodology →